Chamber apparatus and method of maintaining target supply unit

ABSTRACT

A chamber apparatus used with a laser apparatus may include: a chamber provided with at least one inlet for introducing thereinto a laser beam outputted from the laser apparatus; a target supply unit provided to the chamber for supplying a target material to a predetermined region in the chamber; a recovery control unit for instructing the target supply unit to execute recovery operation if a predetermined condition is met; a recovery unit for executing the recovery operation in response to the instruction from the recovery control unit; and a position measuring unit for measuring a position of the target material supplied from the target supply unit into the chamber.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority from Japanese Patent ApplicationNo. 2010-062380 filed Mar. 18, 2010, and Japanese Patent Application No.2011-013014 filed Jan. 25, 2011, the disclosure of each of which isincorporated herein by reference in its entirety.

BACKGROUND

1. Technical Field

The present disclosure relates to a chamber apparatus and to a methodfor maintaining a target supply unit.

2. Related Art

With recent increase in integration of semiconductor process, transferpatterns for use in photolithography of the semiconductor process haverapidly become finer. In the next generation, microfabrication at 70 to45 nm, and further, microfabrication at 32 nm or less is to be demanded.Accordingly, for example, to meet the demand for microfabrication at 32nm or less, an exposure apparatus is expected to be developed, where EUVlight at a wavelength of approximately 13 nm is combined with areduction projection reflective optical system.

There are mainly three types of known EUV light generation apparatuses,namely, a laser produced plasma (LPP) type apparatus using plasmaproduced as a target material is irradiated with a laser beam, adischarge produced plasma (DPP) type apparatus using plasma produced bya discharge, and a synchrotron radiation (SR) type apparatus usingorbital radiation.

SUMMARY

A chamber apparatus according to one aspect of this disclosure may be achamber apparatus used with a laser apparatus, and the chamber apparatusmay include: a chamber provided with at least one inlet for introducingthereinto a laser beam outputted from the laser apparatus; a targetsupply unit provided to the chamber for supplying a target material to apredetermined region in the chamber; a recovery control unit forinstructing the target supply unit to execute recovery operation if apredetermined condition is met; a recovery unit for executing therecovery operation in response to the instruction from the recoverycontrol unit; and a position measuring unit for measuring a position ofthe target material supplied from the target supply unit into thechamber.

A method for maintaining a target supply unit according to anotheraspect of this disclosure may be a method for maintaining a targetsupply unit in a chamber apparatus including a chamber, the targetsupply unit, a recovery control unit, a recovery unit, and a positionmeasuring unit, and the method may include: acquiring determinationinformation indicative of whether or not recovery operation is to beexecuted for the target supply unit; determining whether or not it istiming at which the recovery operation can be executed if it isdetermined that the recovery operation is to be executed; instructingthe recovery unit by the recovery control unit to execute the recoveryoperation if it is determined that it is the timing at which therecovery operation can be executed; and executing predetermined recoveryoperation by the recovery unit in response to the instruction by therecovery control unit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates the general configuration of an EUVlight generation apparatus according to a first embodiment of thisdisclosure.

FIG. 2 schematically illustrates the configuration of a target supplyunit and a pressure control unit according to the first embodiment.

FIG. 3 is a flowchart of processing for setting a recovery flag.

FIG. 4 is a flowchart showing recovery control processing.

FIG. 5 is a flowchart showing processing in a normal mode.

FIG. 6 schematically illustrates the configuration for removing aforeign matter according to a second embodiment.

FIG. 7 schematically illustrates the configuration for removing aforeign matter according to a third embodiment.

FIG. 8 schematically illustrates the configuration for removing aforeign matter according to a fourth embodiment.

FIG. 9 schematically illustrates the configuration for removing aforeign matter according to a fifth embodiment.

FIG. 10 is an enlarged view of a target supply unit.

FIG. 11 schematically illustrates the configuration for removing aforeign matter according to a sixth embodiment.

FIG. 12A schematically illustrates the configuration for removing aforeign matter according to a seventh embodiment.

FIG. 12B is a sectional view of a nozzle unit and a gas pipe accordingto the seventh embodiment.

FIG. 13 schematically illustrates the configuration for removing aforeign matter according to an eighth embodiment.

FIG. 14A schematically illustrates the configuration for removing aforeign matter according to a ninth embodiment.

FIG. 14B is a sectional view of an insulator and a gas channel accordingto the ninth embodiment.

FIG. 15 is a sectional view of a target supply unit according to a tenthembodiment.

FIG. 16A schematically illustrates the configuration for removing aforeign matter according to an eleventh embodiment.

FIG. 16B is a sectional view of a nozzle unit and a gas pipe accordingto the eleventh embodiment.

FIG. 17A schematically illustrates the configuration for removing aforeign matter according to a twelfth embodiment.

FIG. 17B is a sectional view of an insulator and a gas channel accordingto the twelfth embodiment.

FIG. 18 schematically illustrates the configuration for removing aforeign matter according to a thirteenth embodiment.

FIG. 19 is a sectional view of a target supply unit according to afourteenth embodiment.

FIG. 20A schematically illustrates the configuration for removing aforeign matter according to a fifteenth embodiment.

FIG. 20B schematically illustrates the configuration for removing aforeign matter according to the fifteenth embodiment.

FIG. 21A schematically illustrates the configuration for removing aforeign matter according to a sixteenth embodiment.

FIG. 21B schematically illustrates the configuration for removing aforeign matter according to the sixteenth embodiment.

FIG. 22A schematically illustrates the configuration for removing aforeign matter according to a seventeenth embodiment.

FIG. 22B schematically illustrates the configuration for removing aforeign matter according to the seventeenth embodiment.

FIG. 23A schematically illustrates the configuration for removing aforeign matter according to an eighteenth embodiment.

FIG. 23B schematically illustrates the configuration for removing aforeign matter according to the eighteenth embodiment.

FIG. 23C schematically illustrates the configuration for removing aforeign matter according to the eighteenth embodiment.

FIG. 24 is a descriptive view schematically illustrating theconfiguration for protecting a collector mirror from a foreign matter.

FIG. 25A is a descriptive view schematically illustrating theconfiguration for switching positions of a protective cover.

FIG. 25B is a descriptive view schematically illustrating theconfiguration for switching the positions of the protective cover.

FIG. 26 is a descriptive view schematically illustrating theconfiguration for protecting a collector mirror from a foreign matteraccording to a twentieth embodiment.

FIG. 27 is a flowchart of processing for setting a recovery flag.

FIG. 28 is a flowchart of another processing for setting a recoveryflag.

FIG. 29 is a flowchart of yet another processing for setting a recoveryflag.

FIG. 30 is a flowchart of still another processing for setting arecovery flag.

DESCRIPTION OF PREFERRED EMBODIMENTS

Hereinafter, embodiments of this disclosure will be described in detailwith reference to the drawings. The embodiments described below areexamples of this disclosure, and do not limit the contents of thisdisclosure. Also, configurations and operations described according tothe respective embodiments may not all be essential configurations andoperations for this disclosure. It should be noted that like elementsare referenced by like reference numerals, and duplicate descriptionthereof will be omitted.

First Embodiment

A first embodiment will be described with reference to FIGS. 1 to 5.FIG. 1 schematically illustrates the general configuration of an EUVlight generation apparatus 1. The EUV light generation apparatus 1 mayinclude, for example, a vacuum chamber 100, a driver laser device 110, atarget supply unit 120, an EUV collector mirror 130, a vacuum pump 140,partition walls 150 and 151 having apertures, a gate valve 160, an EUVlight generation controller 300, a droplet controller 310, a pulsecontrol unit 320, and a pressure control unit 330.

Each of the above-described constituent elements (1, 100, 110, 120, 130,140, 150, 151, 160, 300, 310, 320, and 330) may be provided at leastsingly. However, without being limited thereto, each constituent elementmay be provided in plurality.

The vacuum chamber 100 may include a first chamber 101 and a secondchamber 102. The first chamber 101 is a main chamber in which generationof plasma is performed. The second chamber 102 is a connection chamberthrough which EUV light emitted from the plasma is supplied to anexposure apparatus (not illustrated).

The vacuum pump 140 may be connected to the first chamber 101. Withthis, the interior of the chamber 100 may be maintained in alow-pressure state. Further, a configuration may be such that anothervacuum pump is provided for the second chamber 102. In that case, thepressure in the first chamber 101 may be kept lower than the pressure inthe second chamber 102, whereby debris can be prevented from flowinginto the exposure apparatus.

The target supply unit 120 may function as a device for outputting adroplet 201 of, for example, a target material 200 such as tin (Sn),into the chamber 100. The droplet 201 may be a target to be irradiatedwith a laser beam. A main body 121 of the target supply unit 120 maystore the target material 200 in a molten state, and predeterminedpressure can be applied to the interior of the main body 121.

An electrode unit 123, which is an example of an “intermediatestructure,” may be provided at a tip side of a nozzle of the targetsupply unit 120. When predetermined pulse voltage is applied to theelectrode unit 123, for example, an electric field may be generatedbetween the target material 200 and the electrode unit 123. With this,the droplet 201 may be pulled out from the target supply unit 120, andthe droplet 201 may be outputted into the chamber 100. The configurationof the target supply unit 120 will be described later in detail withreference to FIG. 2. Further, the output of the droplet is not limitedto the method in which the electric field is used as described above.For example, the pressure may be applied to a molten target material,whereby the droplet 201 may be outputted.

The driver laser device 110 may output a pulsed laser beam L1 forturning the droplet 201 into plasma. The driver laser device 110 may beconfigured, for example, as a CO₂ (carbon dioxide gas) pulsed laserdevice. The driver laser device 110 may output the laser beam L1 havingsuch specifications as a wavelength of 10.6 μm, an output of 20 kW, apulse repetition rate in a range from 30 to 100 kHz, and a pulse widthof 20 nsec. However, the specifications of the driver laser device 110are not limited to the above-mentioned example. Further, theconfiguration may be such that a laser device aside from the CO₂ pulsedlaser device is used.

The laser beam L1 outputted from the driver laser device 110 may enterthe first chamber 101 via a focusing lens 111, a window 112, and soforth. The laser beam L1, having entered the first chamber 101, may passthrough a through hole 131 provided in the EUV collector mirror 130, andmay strike the droplet 201.

When the droplet 201 is irradiated with the laser beam L1, the droplet201 may be turned into plasma in a plasma generation region 202. Theplasma may emit light containing EUV light L2 at a wavelength ofapproximately 13.5 nm.

The EUV light L2 emitted from the plasma may be incident on a collectormirror 130 for collecting EUV, and reflected by the collector mirror130. The collector mirror 130 may have the reflection surface thereofformed in a spheroid shape. The EUV light L2 reflected by the collectormirror 130 may be focused at IF (Intermediate Focus) in the secondchamber 102. The EUV light L2 focused at IF may be guided to theexposure apparatus through the gate valve 160 in an open state.

In the first embodiment, the droplet 201 may be generated in an amountrequired for the generation of the EUV light in accordance with thefrequency at which a laser beam is outputted from the driver laserdevice 110. Hence, the amount of debris generated may be small. However,in order to reduce an adverse effect caused by the debris, for example,two magnetic-field generation coils (not shown) may be provided suchthat the two magnetic-field generation coils face each other, with anoptical path of the EUV light L2 therebetween, in the up-down directionof the sheet surface or in the direction perpendicular to the sheetsurface of FIG. 1. Ionic debris may be trapped in a magnetic fieldgenerated with the magnetic-field generation coils.

The two partition walls 150 and 151 may be disposed in the vicinity ofIF. The travel direction of the EUV light L2 reflected by the collectormirror 130 being the reference, the first partition wall 150 may beprovided upstream of IF, and the second partition wall 151 may beprovided downstream of IF. The partition walls 150 and 151 may, forexample, have apertures of approximately several millimeters to 10 mm,respectively.

The first partition wall 150 may be provided near a position at whichthe first chamber 101 is connected to the second chamber 102. The secondpartition wall 151 may be provided near a position at which the secondchamber 102 is connected to the exposure apparatus. Note that theconfiguration may be such that an SPF (Spectral Purity Filter) isprovided at least one of the upstream side and the downstream side ofIF, so that light at a wavelength of other than 13.5 nm is shielded.

Next, the configuration pertaining to the control in the EUV lightgeneration apparatus 1 will be described. The EUV light generationcontroller 300 may control the operation of the EUV light generationapparatus 1. The EUV light generation controller 300 may giveinstructions to the droplet controller 310 and to the driver laserdevice 110. In response to the instructions, the droplet 201 may beoutputted at predetermined timing. The outputted droplet 201 may beirradiated with the pulsed laser beam L1. Further, the EUV lightgeneration controller 300 may control the operation of the vacuum pump140, the gate valve 160, and so forth.

The EUV light generation controller 300 may include at least onerecovery control unit 301 and at least one position measuring unit 302.The recovery control unit 301 may have a function of causing a recoveryunit 400 to automatically perform maintenance on the target supply unit120, when, for example, the above occurs to the target supply unit 120,thereby allowing the target supply unit 120 to recover to a normalstate. The position measuring unit 302 may have a function of measuringthe position of the droplet 201 based on a signal from at least oneposition detection sensor 340, and notifying the recovery control unit301 of the result. A method of recovery control will be described later.

The recovery control unit 301 and the position measuring unit 302 may beconfigured as controllers separate from the EUV light generationcontroller 300, or may be configured as controllers provided in thedroplet controller 310.

The position detection sensor 340 may be configured as a sensor that candetect the position of the droplet 201, and may, for example, be acamera, an optical sensor, an electromagnetic sensor, or the like. Theconfiguration may be such that a plurality of the position detectionsensors 340 of the same type or of different types is provided.

The droplet controller 310 may control the operation of the targetsupply unit 120. The pulse control unit 320 and the pressure controlunit 330 may be connected to the droplet controller 310.

The pulse control unit 320 may function to apply predetermined pulsevoltage to the electrode unit 123 provided at a leading end of thetarget supply unit 120. The pulse control unit 320 may include: forexample, at least one high-voltage DC power supply device; at least oneswitching driver that outputs, as a pulse, DC high voltage inputted fromthe high-voltage DC power supply device; and at least one pulsegenerator that inputs the pulse frequency to the switching driver (notshown).

The pressure control unit 330 may function to apply predeterminedpressure to the interior of the main body 121 of the target supply unit120. The interior of the main body 121 may be controlled atpredetermined pressure with inert gas (for example, argon gas) suppliedvia the pressure control unit 330.

FIG. 2 schematically illustrates the configuration of the target supplyunit 120 and the pressure control unit 330. The configuration of thetarget supply unit 120 will be described first. The target supply unit120 may include, for example, at least one main body 121, at least onenozzle unit 122, at least one electrode unit 123, at least one insulator124, and at least one heating unit 125.

The main body 121 may store the target material 200. The main body 121may be mounted to the chamber 100 such that the tip 121A thereofprotrudes into the first chamber 101. A storage 121B for storing thetarget material 200 may be provided in the main body 121. An outputchannel 121C may be provided in the tip 121A.

The storage 121B may be connected to the pressure control unit 330 via apipe 126 that is connected to a base end side of the main body 121. Theoutput channel 121C may allow communication between the storage 121B andthe nozzle unit 122. The inert gas supplied via the pressure controlunit 330 may be supplied into the storage 121B of the main body 121 viathe pipe 126.

The heating unit 125 may be provided on an outer surface of the mainbody 121. The heating unit 125 may be configured, for example, of anelectric heater or the like. The heating unit 125 applies heat such thatthe temperature of the target material 200 (for example, tin) in themain body 121 is maintained approximately at 300° C. It is to be notedthat the value of 300° C. is an example, and this disclosure is notlimited to that value. That is, it is sufficient as long as the targetmaterial 200 is liquid at a given temperature.

The nozzle unit 122 may, for example, be formed in a disc shape. Acircular output hole 122A may be formed at the center of the nozzle unit122. The output hole 122A and the storage 121B of the main body 121 maypreferably be in communication with each other via the output channel121C. Further, a conical nozzle 122B facing downward may be provided,integrally with the nozzle unit 122, at the lower surface of the nozzleunit 122 such that the nozzle 122B protrudes toward the plasmageneration region 202 in the first chamber 101. The nozzle 122B isformed so as to protrude into the first chamber 101, whereby theelectric field may be enhanced at the tip of the nozzle 122B.

The material for the nozzle unit 122 will be described. First, thenozzle unit 122 comes into contact with the target material (forexample, tin); thus, the nozzle unit 122 is preferably made of amaterial that is not susceptible to chemical or physical corrosion orerosion by tin. A property of not being susceptible to corrosion/erosionby tin is herein referred to as “corrosion/erosion resistance” to tin.Materials having the corrosion/erosion resistance to tin may include,for example, molybdenum (Mo), tungsten (W), tantalum (Ta), titanium(Ti), stainless steel, diamond, ceramics, and so forth. Also, materialsother than ceramics may include silicon carbide, silicon nitride,aluminum oxide, zirconium oxide, diamond, silicon oxide, molybdenumoxide, tantalum oxide, tungsten oxide, and so forth. Ceramics mayinclude ceramics containing, as a main component, silicon carbide,silicon nitride, aluminum oxide, zirconium oxide, diamond, siliconoxide, molybdenum oxide, tantalum oxide, tungsten oxide, and so forth.It is to be noted that, in the first embodiment, tin is cited as anexample of the target material; however, the target material is notlimited to tin. In the case where a material other than tin is used asthe target material, the nozzle unit 122 may preferably be formed of adesirable material having the corrosion/erosion resistance to the givenmaterial. In the description to follow as well, tin will be described asthe target material for a mere example; however, the target material isnot limited to tin. In any case, in the case where a material other thantin is used as the target material, constituent elements describedhereinafter to preferably have the corrosion/erosion resistance to tinmay be configured of a desirable material having the corrosion/erosionresistance to the given material.

Second, from the viewpoint of enhancing the electric field at the tip ofthe nozzle unit 122, the nozzle unit 122 preferably has an electricalinsulating property. Among the materials having the corrosion/erosionresistance to tin, diamond or ceramics is known as a material having anelectrical insulating property. Hence, the nozzle unit 122 maypreferably be configured of diamond or ceramics. However, without beinglimited thereto, a nozzle unit formed of a material aside from diamondor ceramics is included in the scope of this disclosure. For example,materials other than ceramics may include silicon carbide, siliconnitride, aluminum oxide, zirconium oxide, diamond, silicon oxide,molybdenum oxide, tantalum oxide, tungsten oxide, and so forth. Ceramicsmay include ceramics containing, as a main component, silicon carbide,silicon nitride, aluminum oxide, zirconium oxide, diamond, siliconoxide, molybdenum oxide, tantalum oxide, tungsten oxide, and so forth.

The main body 121 is at least required to have the corrosion/erosionresistance to tin. Of the entirety of the main body 121, part that comesinto contact with tin may preferably have the corrosion/erosionresistance to tin.

The disc-shaped electrode unit 123 having a through hole provided at thecenter thereof may be provided below the nozzle unit 122 so as to bedistanced from the nozzle unit 122 with the insulator 124 arrangedtherebetween. An output hole 123A of the electrode unit 123 maypreferably be coaxial with the nozzle 122B. A predetermined gap may beformed between the output hole 123A and the tip of the nozzle 122B.

The material for the electrode unit 123 will be described. The electrodeunit 123 may come into contact with tin; thus, the electrode unit 123may preferably have the corrosion/erosion resistance to tin. Theelectrode unit 123 may further have resistance to sputtering. This isbecause tin particles, at high speed, from plasma may collide with asurface of the electrode unit 123. Further, the electrode unit 123 maypreferably have electrical conductivity. The conditions above beingconsidered, the electrode unit 123 may preferably be formed, forexample, of molybdenum, tungsten, tantalum, titanium, stainless steel,and so forth.

Part of the droplet 201 may adhere to the electrode unit 123, and remainthereon as a foreign matter 210 (see FIG. 6). Hence, in embodimentsdescribed hereinafter, the electrode unit 123, which is an intermediatestructure located between the nozzle unit 122 and the plasma generationregion 202, may preferably be formed of a material having a lowwettability to the target material 200. With this, the foreign matter210 adhering to the electrode unit 123 can be allowed to drop and beremoved. Accordingly, the electrode unit 123, for example, maypreferably be formed of metal, such as molybdenum or tungsten, orceramics such as alumina; or the electrode unit 123 may preferably becoated with such a material. Coating materials may include siliconcarbide, silicon nitride, zirconium oxide, diamond, silicon oxide,molybdenum oxide, tantalum oxide, or tungsten oxide, or ceramicscontaining such a material as a main component.

The insulator 124 may be provided such that at least part thereof isarranged between the nozzle unit 122 and the electrode unit 123. A space124A may be formed at an inner circumferential side of the insulator124. The nozzle 122B may be provided so as to protrude into the space124A. The nozzle 122B and the output hole 123A may preferably becoaxial.

The insulator 124 may preferably provide an insulating function and aheat transferring function, aside from a function of positioning thenozzle unit 122 and the electrode unit 123. The insulating function is afunction of providing electrical insulation between the nozzle unit 122and the electrode unit 123. The heat transferring function is a functionof transmitting heat generated at the heating unit 125 to the electrodeunit 123. With this, the temperatures of the nozzle unit 122 and of theelectrode unit 123 may be made higher than the melting point of tin,whereby tin can be prevented from being fixed on the nozzle unit 122 andthe electrode unit 123.

The material for the insulator 124 will be described. The insulatingfunction and the heat transferring function being considered, theinsulator 124 may preferably be constituted of a material with a highinsulating property and a high thermal conductivity. Hence, theinsulator 124, for example, may be constituted of a material, such asaluminum nitride (AlN), diamond, or the like. Alternatively, theinsulator 124 may be constituted of ceramics containing, as a maincomponent, silicon carbide, silicon nitride, aluminum oxide, zirconiumoxide, diamond, silicon oxide, molybdenum oxide, tantalum oxide,tungsten oxide, and so forth.

The configuration of the pressure control unit 330 will be described.The pressure control unit 330 may include, for example, a pressurecontroller 331, a pressure adjusting valve 332, a discharge pump 333, asupply valve 334, and a discharge valve 335. The pressure control unit330 may supply gas from a gas supply unit 336 into the main body 121 ofthe target supply unit 120 via the pressure adjusting valve 332, or thelike. As the gas for applying pressure to the target material 200, argongas is used in the first embodiment; however, inert gas aside from argongas may be used.

The pressure adjusting valve 332 may adjust the pressure of gas suppliedfrom the gas supply unit 336 and to be sent into the pipe 126 topredetermined pressure set by the pressure controller 331, and may sendthe gas into the pipe 126. The pipe 126 may constitute part of a gaschannel from the pressure adjusting valve 332 to the main body 121. Thegas, the pressure of which has been adjusted to the predeterminedpressure, may be supplied into the main body 121 via the supply valve334 provided midway in the piping leading to the pipe 126.

The discharge pump 333 is a pump for discharging the gas inside the mainbody 121. In a state in which the supply valve 334 is closed and thedischarge valve 335 provided midway in a discharge channel 126A is open,the discharge pump 333 may be actuated. With this, the gas in the mainbody 121 may be discharged.

In a state in which constant pressure is applied to the target material200, pulse voltage is applied to the electrode unit 123 at predeterminedtiming. The predetermined timing may preferably set to correspond to thefrequency of the laser beam L1 outputted from the driver laser device110. The pulse voltage may be a rectangular wave, a triangular wave, asinusoidal wave, and so forth.

When the gas applies pressure to the target material 200 in the storage121B, the target material 200 may slightly protrude from the nozzle122B. However, in this state, the target material 200 is not outputtedthrough the nozzle 122B. That is, meniscus protruding downward may beformed at the nozzle 122B.

In the state in which the gas applies pressure to the target material200, when the pulse voltage is applied to the electrode unit 123, thetarget material 200 slightly protruding from the nozzle 122B may beseparated from the tip of the nozzle with electrostatic attractiveforce. The target material 200 pulled out through the nozzle 122B may beoutputted as the droplet 201 toward the plasma generation region 202.The droplet 201, which has been separated with the electrostaticattractive force, is electrically charged.

In the first embodiment, in the state in which the gas applies pressureto the target material 200 in the main body 121, the pulse voltage isapplied to the electrode unit 123 provided so as to face the nozzle122B. With this, in the first embodiment, the droplet 201 of a requiredsize can be outputted through the nozzle 122B as required.

FIG. 3 is a flowchart showing processing for setting a recovery flag.The recovery flag is information indicating that timing at whichrecovery operation should be executed has come. The recovery operationis, for example, operation of removing the foreign matter 210 from thetarget supply unit 120 so that the target material 200 can be outputtedfrom the target supply unit 120 accurately toward the plasma generationregion 202. This processing may be executed by the recovery control unit301.

The recovery control unit 301 may acquire determination information(S10), and determine whether or not a condition for setting the recoveryflag is met (S11). If the setting condition is met (S11: YES), therecovery control unit 301 may set the recovery flag (S12). If thesetting condition is not met (S11: NO), the processing may return toS10.

The determination information is information used to determine whetheror not the recovery flag should be set. As the determinationinformation, for example, an elapsed time since the preceding recoveryoperation, the number of times the target supply unit 120 has beenstarted, an integrated operating time of the target supply unit 120,positional accuracy of the droplet 201 in the plasma generation region202, and so forth, may be cited as examples. Further, the number oftimes or the duration in which the target supply unit 120 has beenheated, the number of times or the duration in which the droplet 201 hasbeen outputted, and so forth, may be used as the determinationinformation as well.

The recovery control unit 301 may determine whether or not the recoveryflag should be set, based on at least one of the above-mentioneddetermination information. Specific examples in which the determinationinformation is used will be described later in another embodiment.

FIG. 4 is a flowchart of recovery control processing. The recoverycontrol unit 301 may determine whether or not the recovery flag is set(S20). If the recovery flag is not set (S20: NO), the recovery controlunit 301 may shift to a normal mode (S26). The content of processing inthe normal mode will be described later with reference to FIG. 5.

If the recovery flag is set (S20: YES), the recovery control unit 301may determine whether or not it is the timing available for recovery(S21). If it is not the timing available for recovery (S21: NO), therecovery control unit 301 may shift to the normal mode (S26).

The timing available for recovery means timing at which the recoveryoperation can be executed. For example, even if the recovery flag isset, while exposure works are carried out in the exposure apparatus, theoutput of the EUV light cannot be stopped. The EUV light generationapparatus 1 needs to continue supplying the EUV light until a series ofworks is ended. Hence, in the first embodiment, for example, theprocessing may wait for timing at which the works in the exposureapparatus stop for a given period of time, and when the stop for thegiven period of time is ensured, the recovery operation may be executed.The recovery control unit 301 can determine the timing at which theworks in the exposure apparatus are stopped for the given amount oftime, by communicating with the exposure apparatus or by acquiring asignal from the exposure apparatus.

If the timing is the timing available for recovery (S21: YES), therecovery control unit 301 may shift to a recovery mode (S22). Therecovery control unit 301 may give an instruction to the recovery unit400 and hence may cause the recovery unit 400 to execute the recoveryoperation (S23).

After the recovery operation is executed, the recovery control unit 301may cause the target supply unit 120 to execute test operation (S24).The test operation is so-called test shooting, and the target supplyunit 120 may be made to output the droplet 201 by a predetermined numberor for a predetermined period of time.

The recovery control unit 301 may determine whether or not thepositional accuracy of the droplet 201, which has been outputted fromthe target supply unit 120, in the plasma generation region 202 iswithin a predetermined range, based on the measurement result by theposition measuring unit 302 (S25).

For example, the recovery control unit 301 may determine whether or notthe value of a positional variation (3σ) of the droplet 201 is equal toor smaller than 1/n (for example, n=2 to 3) of a diameter D of thedroplet 201. The value of n is an example.

If the positional accuracy of the droplet 201 from the test shooting iswithin the predetermined range (S25: YES), the recovery control unit 310may shift from the recovery mode to the normal mode (S26). In contrast,if the positional accuracy of the droplet 201 is not within thepredetermined range (S25: NO), the recovery control unit 301 may causethe recovery unit 400 to execute the recovery operation again (S23).

FIG. 5 is a flowchart showing the detail of the normal mode processing(S26) shown in FIG. 4. The recovery control unit 301 may acquire theposition of the droplet 201, based on the measurement result from theposition measuring unit 302 (S260). It is to be noted that the normalmode is a state in which the droplet 201 is outputted at predeterminedtiming. When the droplet 201 outputted in the normal mode is irradiatedwith the pulsed laser beam L1, the generated EUV light L2 may be focusedat IF and then guided to the exposure apparatus.

The recovery control unit 301 may determine whether or not thepositional accuracy of the droplet 201 in the plasma generation region202 is within the predetermined range (S261). If the positional accuracyof the droplet 201 is within the predetermined range (S261: YES), therecovery control unit 301 may remain in the normal mode (S262). This isbecause the droplet 201 outputted from the target supply unit 120 isconsidered to substantially accurately be arriving at the plasmageneration region 202.

If the positional accuracy of the droplet 201 is not within thepredetermined range (S261: NO), the recovery control unit 301 may shiftfrom the normal mode to the recovery control processing (S263). When therecovery control unit 301 shifts to the recovery control processing, therecovery flag may be set. With this, the processing following S21 shownin FIG. 4 may be executed. As described above, the recovery operationfor recovering the function of the target supply unit 120 may beexecuted at proper timing. Although not shown, if the function is notrecovered even in the recovery mode, this may be notified through analert or communication.

According to the first embodiment thus configured, since the recoveryoperation can be automatically executed, an operator does not constantlyhave to monitor the output state of the droplet, and maintenanceefficiency may be increased.

Further, in the first embodiment, by temporarily executing the recoveryoperation without completely stopping the target supply unit 120, thetarget supply unit 120 can be recovered to the normal state.Accordingly, a time for maintaining the target supply unit 120 can bedecreased, and an operating rate can be increased. Consequently, workingefficiency of the exposure works can be increased.

Further, in the first embodiment, since recovery of the target supplyunit 120 is carried out in consideration of the situation of adownstream process (exposure works), usability of the apparatus may beincreased.

Second Embodiment

A second embodiment will be described with reference to FIG. 6.Embodiments described below may correspond to modifications of the firstembodiment. Hence, the description is given mainly for points differentfrom the first embodiment. In the second embodiment, a specific exampleof the recovery unit 400 will be described.

FIG. 6 is a descriptive view showing the tip of the target supply unit120 in enlargement. The intermediate structure 500 may be provided so asto face the nozzle unit 122. A specific example of the intermediatestructure 500 may be the electrode unit 123 shown in FIG. 2. Theintermediate structure 500 is not limited to the electrode unit 123 towhich pulsed voltage is applied for pulling out the target material 200through the nozzle unit 122.

The intermediate structure 500 may be disposed between the nozzle unit122 and the plasma generation region 202, and the foreign matter 210derived from the droplet 201 or the like may adhere to the intermediatestructure 500. Since the droplet 201 is electrically charged, the movingpath and the speed thereof can be changed with an electric field or amagnetic field. Thus, by disposing the intermediate structure 500 at aproper position, the movement of the droplet 201 can be controlled. Asthe intermediate structure 500 aside from the electrode unit 123, forexample, an electrostatic lens for correcting the moving path of thedroplet 201, an acceleration electrode for increasing the speed of thedroplet 201, and so forth, may be cited as examples. Also, without beinglimited thereto, the moving path of the droplet 201 may be corrected byusing a permanent magnet, an electromagnetic coil, and so forth. Thepermanent magnet and the electromagnetic coil may be included in theintermediate structure 500.

A heater 410, which is an example of the recovery unit 400, may beprovided on a lower surface of the intermediate structure 500. Theheater 410, for example, may be formed annularly so as to cover thelower surface of the annular intermediate structure 500. The heater 410may heat the foreign matter 210 adhering to the intermediate structure500 so as to melt the foreign matter 210. The foreign matter 210 may beformed as the entirety or part of a single droplet 201 adheres to theintermediate structure 500. The heater 410 generates heat at atemperature exceeding the melting point of the target material 200 whena heater power supply 415 receives a signal outputted from the recoverycontrol unit 301 and the electric power is supplied from the heaterpower supply 415 to the heater 410. Note that the intermediate structure500 may be provided with a temperature sensor (not shown).

The foreign matter 210 molten with the heat from the heater 410 may fallfrom the intermediate structure 500 due to the gravity. The moltenforeign matter 210 may drop, for example, through an opening 501 formedat the center of the intermediate structure 500.

In order to prevent the foreign matter 210 removed from the intermediatestructure 500 from adhering to a component (for example, the collectormirror 130) arranged below the target supply unit 120, a configurationfor trapping the removed foreign matter 210 or a configuration forprotecting the collector mirror 130 from the foreign matter 210 may beprovided in embodiments described later.

The second embodiment thus configured yields an advantage similar tothat of the first embodiment. In the second embodiment, the foreignmatter 210 adhering to the intermediate structure 500 may be molten andremoved with the heat from the heater 410. Accordingly, the moving pathof the droplet 201 can be prevented from being deviated due to theforeign matter 210 adhering to the intermediate structure 500, and thepositional accuracy of the droplet 201 can be increased.

Third Embodiment

A third embodiment will be described with reference to FIG. 7. In thethird embodiment, a heater 411, which is an example of the recovery unit400, may be provided on an outer peripheral surface of the intermediatestructure 500. The heater 411 is formed in a short cylindrical shape soas to cover the outer peripheral surface of the annular intermediatestructure 500.

FIG. 7 is a descriptive view showing the tip of the target supply unit120 in enlargement. As in the second embodiment, the intermediatestructure 500 being heated with the heater 411, the foreign matter 210adhering to the surface of the intermediate structure 500 may be made tomelt and drop to be removed. The third embodiment thus configured mayyield an advantage similar to that of the second embodiment.

Fourth Embodiment

A fourth embodiment will be described with reference to FIG. 8. FIG. 8is a descriptive view showing the tip of the target supply unit 120 inenlargement. In the fourth embodiment, an annular heater 412 may beprovided on an upper surface of the intermediate structure 500. With thefourth embodiment thus configured as well, the foreign matter 201 may bemade to melt with the heat from the heater 412 and be removed.

Fifth Embodiment

A fifth embodiment will be described with reference to FIGS. 9 and 10.In the fifth embodiment, the intermediate structure 500 may be heatedwith the target material 200 stored in the storage 121B, whereby theforeign matter 210 adhering to the intermediate structure 500 may beremoved.

FIG. 9 is a descriptive view showing the tip of the target supply unit120 in enlargement. An annular heating pipe 413 may be provided so as tosurround the outer peripheral surface of the intermediate structure 500.The target material 200 in the molten state stored in the target supplyunit 120 may be supplied into the heating pipe 413, which is an exampleof the recovery unit 400.

The entire intermediate structure 500 may be heated with the heatconducted from the target material 200 flowing in the heating pipe 413.With this, the foreign matter 210 adhering to the intermediate structure500 may melt and drop.

The configuration shown in FIG. 10 may correspond to a modification ofthe fifth embodiment. As shown in FIG. 10, the heating pipe 413 may beprovided so as to surround an outer periphery of the insulator 124. Thestorage 121B may be provided with an outlet port 121D1 through which thetarget material 200 flows out, and an inlet port 121D2 through which thetarget material 200 flows in. The heating pipe 413 may be connected tothe storage 121B via a channel 413A, the inlet port 121D2, and theoutlet port 121D1. The channel 413A may be provided with a pump 413B. Afilter unit for removing an impurity in the target material 200 may beprovided in the channel 413A.

The target material 200 in the storage 121B may flow into the heatingpipe 413 via the outlet port 121D1 and the channel 413A. The targetmaterial 200 flowing through the heating pipe 413 may heat theintermediate structure 500 via the insulator 124.

The target material 200, which has heated the intermediate structure500, may be returned from the heating pipe 413 into the storage 121B viathe channel 413A, the pump 413B, and the inlet port 121D2. The targetmaterial 200 returned into the storage 121B may be heated by the heatingunit 125. The fifth embodiment thus configured may yield an advantagesimilar to those of the above-described embodiments.

Sixth Embodiment

A sixth embodiment will be described with reference to FIG. 11. In thesixth embodiment, the intermediate structure 500 may be heated with anelectromagnetic wave source 414, whereby the foreign matter 210 adheringto the intermediate structure 500 may be removed. FIG. 11 is adescriptive view showing the tip of the target supply unit 120 inenlargement.

The electromagnetic wave source 414, which is an example of the recoveryunit 400, may output, for example, an electromagnetic wave, such as aninfrared laser beam, a microwave, and so forth. The electromagnetic waveoutputted from the electromagnetic wave source 414 may strike theintermediate structure 500, whereby the intermediate structure 500 maybe heated.

Surface roughness of the intermediate structure 500 may be set so thatthe electromagnetic wave may be absorbed well by the intermediatestructure 500. Alternatively, the configuration may be such that theintermediate structure 500 may be entirely or partly (for partirradiated with the electromagnetic wave) coated with a material thatcan easily absorb the electromagnetic wave. Further, the configurationmay be such that the electromagnetic wave may directly strike theforeign matter 210. The sixth embodiment thus configured may yield anadvantage similar to those of the above-described embodiments.

Seventh Embodiment

A seventh embodiment will be described with reference to FIGS. 12A and12B. In the seventh embodiment, inert gas such as argon gas may be usedto blow off and remove the foreign matter 210 adhering to theintermediate structure 500. FIG. 12A is a descriptive view showing thetip of the target supply unit 120 in enlargement. FIG. 12B is asectional view of the nozzle unit 120 and a gas pipe 420.

As shown in FIG. 12A, a tip of the gas pipe 420, which is an example ofthe recovery unit 400, may be provided between the intermediatestructure 500 and the nozzle unit 122. Gas from a gas source 420A, inwhich inert gas such as argon gas is stored, may be blown, via the gaspipe 420, into a space between the nozzle unit 120 and the intermediatestructure 500 by opening a valve 470, whereby the foreign matter 210 maybe removed. The valve 470 may be opened and closed in accordance with asignal from the recovery control unit 301. In the seventh embodiment,the valve 470 is described as a solenoid valve; however, the valve 470may be a valve that is actuated with air pressure.

The seventh embodiment thus configured may yield an advantage similar tothose of the above-described embodiments. In the seventh embodiment,since the gas is blown against the foreign matter 210, whereby theforeign matter 210 may be removed, the intermediate structure 500 maynot need to be heated. However, if the intermediate structure 500 isheated and the foreign matter 210 thereon is in the molten state, theforeign matter 210 can be removed more easily.

Eighth Embodiment

An eighth embodiment will be described with reference to FIG. 13. In theeighth embodiment, a gas channel 421, which is an example of therecovery unit 400, may be provided in the intermediate structure 500.FIG. 13 is a descriptive view showing the tip of the target supply unit120 in enlargement.

In the intermediate structure 500, the gas channel 421 may be formed ina radial direction thereof. One end of the gas channel 421 may beconnected to the gas source 420A. The other end of the gas channel 421may communicate with an opening 501 formed at the center of theintermediate structure 500.

The inert gas blown through the gas channel 421 toward the opening 501may blow away and remove the foreign matter 210 adhering to an areaaround the opening 501. The eighth embodiment thus configured may yieldan advantage similar to that of the seventh embodiment.

Ninth Embodiment

A ninth embodiment will be described with reference to FIGS. 14A and14B. In the ninth embodiment, a gas channel 422, which is an example ofthe recovery unit 400, may be provided in the insulator 124. FIG. 14A isa descriptive view showing the tip of the target supply unit 120 inenlargement. FIG. 14B is a sectional view of the insulator 124 and thegas channel 422.

In the cylindrical insulator 124, the gas channel 422 may be formed in aradial direction thereof. One end of the gas channel 422 may beconnected to the gas source 420A, and the other end of the gas channel422 may communicate with a space 124A between the nozzle unit 122 andthe electrode unit 123.

The inert gas blown through the gas channel 422 into the space 124A maycirculate within the space 124A, and blow away the foreign matter 210 inthe space 124A. The foreign matter 210, which has been blown away, maybe discharged outside through the output hole 123A. The ninth embodimentthus configured may yield an advantage similar to that of the seventhembodiment.

Tenth Embodiment

A tenth embodiment will be described with reference to FIG. 15. In thetenth embodiment, a gas channel 423, which is an example of the recoveryunit, may be provided to the main body 121 of the target supply unit120. FIG. 15 is a sectional view of the target supply unit 120.

The gas channel 423, for example, may be provided to the target supplyunit 120 so as to penetrate through the heating unit 125 and the mainbody 121. One end of the gas channel 423 may be connected to the gassource 420A, and the other end of the gas channel 423 may communicatewith the space 124A between the nozzle unit 122 and the electrode unit123.

The other end of the gas channel 423 may be provided so as to face anarea near the output hole 123A of the electrode unit 123. The inert gasblown through the gas channel 423 may blow away the foreign matter 210adhering to the area near the output hole 123A and the foreign matter210 in the space 124A. The foreign matters 210, which have been blownaway, may be discharged outside through the output hole 123A. The tenthembodiment thus configured may yield an advantage similar to that of theseventh embodiment.

Eleventh Embodiment

An eleventh embodiment will be described with reference to FIGS. 16A and16B. The eleventh embodiment may be similar in configuration to theseventh embodiment shown in FIGS. 12A and 12B, and a plurality of thegas pipes 420 may be provided. FIG. 16A is a descriptive view showingthe tip of the target supply unit 120 in enlargement. FIG. 16B is asectional view of the nozzle unit 122 and the gas pipes 420.

As shown in FIG. 16B, the plurality of the gas pipes 420 may be arrangedsuch that the gas pipes 420 are substantially evenly spaced in acircumferential direction to surround the nozzle 122B (in other words,to surround the opening 501 of the intermediate structure 500).

The gas pipes 420 may respectively be connected to the gas source 420A.The inert gas blown through the respective gas pipes 420 may blow awayand remove the foreign matter 210 adhering to the intermediate structure500. Timing at which the inert gas is blown through the gas pipes 420may be made to differ respectively. For example, the configuration maybe such that a given gas pipe 420 being the starting point, the gaspipes 420 may blow the inert gas successively clockwise orcounterclockwise. The eleventh embodiment thus configured may yield anadvantage similar to that of the seventh embodiment. In the eleventhembodiment, since the inert gas can be blown through the plurality ofthe gas pipes 420, the performance of removing the foreign matter 210can be increased, compared with that in the seventh embodiment.

Twelfth Embodiment

A twelfth embodiment will be described with reference to FIGS. 17A and17B. The twelfth embodiment may be similar in configuration to the ninthembodiment shown in FIGS. 14A and 14B, and a plurality of the gaschannels 422 may be provided in the cylindrical insulator 124 such thatthe gas channels 422 are substantially evenly spaced in thecircumferential direction. FIG. 17A is a descriptive view showing thetip of the target supply unit 120 in enlargement. FIG. 17B is asectional view of the insulator 124 and the gas channels 422.

One end of each gas channel 422 may be connected to the gas source 420A,and the other end of each gas channel 422 may communicate with the space124A. The inert gas blown through the gas channels 422 into the space124A may blow away the foreign matter 210 in the space 124A anddischarge the foreign matter 210 to the outside through the output hole123A. Timing at which the inert gas is blown through the gas channelsmay be set to be the same or different respectively. The twelfthembodiment thus configured may yield an advantage similar to that of theseventh embodiment. In the twelfth embodiment, since the inert gas canbe blown through the plurality of the gas channels 422, the performanceof removing the foreign matter 210 can be increased, compared with thatof the ninth embodiment.

It may be easily understood by those skilled in the art that theplurality of the gas channels 423 may be provided even in theconfiguration of the tenth embodiment shown in FIG. 15, as in thetwelfth embodiment.

Thirteenth Embodiment

A thirteenth embodiment will be described with reference to FIG. 18. Inthe thirteenth embodiment, the inert gas may be supplied from theoutside of the nozzle unit 122 into the nozzle unit 122, whereby theforeign matter 210 in the nozzle unit 122 may be removed. FIG. 18 is asectional view of the target supply unit 120.

A cover 430 may be provided so as to airtightly cover the nozzle unit122 and so forth. The cover 430 may be attached by an open/closemechanism 431 such that the cover 430 can be opened and closed. Theopen/close mechanism 431 may cause the cover 430 to cover the nozzleunit 122 and so forth, or may release the cover 430 from the nozzle unit122 and so forth. The open/close mechanism 431 may, for example, beconfigured of a motor, a cylinder, a link mechanism, and so forth.

A gas source 430A may be connected to the interior of the cover 430 viaa gas channel 430B. A plurality of traps 430C for trapping the foreignmatter 210 may be provided on an inner wall of the main body 121. Eachtrap 430C may be configured, for example, as a tapered ring. Each trap430C is preferably mounted such that a space 430D opening upwardly isformed between the trap 430C and the inner wall of the main body 121.

In the thirteenth embodiment, the cover 430, the gas source 430A, thegas channel 430B, the traps 430C, and the open/close mechanism 431 mayconfigure the recovery unit 400.

In the recovery mode, the open/close mechanism 431 may be actuated andhence the nozzle unit 122 and so forth may airtightly be covered withthe cover 430, and then the inert gas may be sent from the gas source430A into the space in the cover 430. At this time, the gas pressure inthe cover 430 may preferably be higher than the pressure in the storage121B. The inert gas sent into the cover 430 may flow into the storage121B via the nozzle unit 122 and so forth. At this time, the foreignmatter 210 in the nozzle unit 122 may be pushed into the storage 121B.

At least part of a plurality of the foreign matters 210 pushed into thestorage 121B, while floating in the target material 200, may be trappedin any of the plurality of the traps 430C and stored in the space 430D.

The thirteenth embodiment thus configured may yield an advantage similarto those of the above-described embodiments. In the thirteenthembodiment, by blowing the inert gas from the outside into the cover430, the foreign matter 210 in the nozzle unit 122 can be pushed backinto the storage 121B. Further, at least part of the foreign matter 210pushed back into the storage 121B can be trapped in any of the pluralityof the traps 430C. With this, the foreign matter 210 may be removed fromthe nozzle unit 122, and the function of the target supply unit 120 canbe recovered to the normal state. Here, the function subject to recoveryis mainly a function of accurately sending the droplet 201 to the plasmageneration region 202.

Fourteenth Embodiment

A fourteenth embodiment will be described with reference to FIG. 19. Inthe fourteenth embodiment, the configuration may be such that theforeign matter 210 in the nozzle unit 122 is sucked to the outside. FIG.19 is a sectional view of the target supply unit 120.

The target supply unit 120 may be provided with a suction tube 440. Oneend of the suction tube 440 may extend toward the output channel 121C inthe tip 121A. The other end of the suction tube 440 may be provided witha suction pump 440A. Further, a collection tank 440B for collectingthereinto the foreign matter 210 and the target material 200 sucked bythe suction tube 440. In the fourteenth embodiment, the suction tube440, the suction pump 440A, and the collection tank 440B may configurethe recovery unit 400.

When the suction pump 440A is actuated, a value (not shown) locatedbetween the suction pump 440A and the target supply unit 120 is opened,and hence the foreign matter 210 and the target material 200 suspendedat the tip of the target supply unit 120 may be sucked through the tipof the suction tube 440 and discharged into the collection tank 440B.The collected target material 200 may be re-used after having theforeign matter 210 removed therefrom.

In the fourteenth embodiment thus configured, since the foreign matter210 in the target supply unit 120 is sucked and removed, the maintenanceon the target supply unit 120 can be performed automatically and theusability of the device can be increased, as in the first embodiment.

Fifteenth Embodiment

A fifteenth embodiment will be described with reference to FIGS. 20A and20B. FIGS. 20A and 20B are sectional views showing the nozzle unit 122in enlargement. In the fifteenth embodiment, by applying vibration tothe nozzle unit 122, the foreign matter 210 suspended in the nozzle unit122 may be crushed and discharged outside. In FIGS. 20A and 20B, theinsulator 124 and the electrode unit 123 are omitted for the sake ofsimplicity.

A vibrator 450, which is an example of the recovery unit 400, may beprovided at an outer periphery side of the nozzle 122B. The vibrator 450may vibrate in accordance with voltage from a high-frequency powersupply 450A. As shown in FIG. 20A, when the vibrator 450 vibrates, theforeign matter 210 may be crushed into small pieces by the vibration. Asshown in FIG. 20B, the foreign matter 210, which has been crushed intosmall pieces, may be discharged outside of the nozzle 122B.

With the fifteenth embodiment thus configured as well, the maintenanceon the target supply unit 120 can be performed automatically, and anadvantage similar to that of the first embodiment may be yielded.

Sixteenth Embodiment

A sixteenth embodiment will be described with reference to FIGS. 21A and21B. In the sixteenth embodiment, by heating the nozzle unit 122, theforeign matter 210 suspended in the nozzle unit 122 may be molten anddischarged. FIGS. 21A and 21B are sectional views showing the nozzleunit 122 in enlargement. A heater 460, which is an example of therecovery unit 400, may be provided at the outer periphery side of thenozzle 122B.

As shown in FIG. 21A, the heater 460 generates heat with the electricpower supplied from a heater power supply 460A. The heater 460 is heatedto a temperature at which the foreign matter 210 is molten. As shown inFIG. 21B, the molten foreign matter may be discharged outside throughthe nozzle 122B. The sixteenth embodiment thus configured as well mayyield an advantage similar to that of the fifteenth embodiment.

Seventeenth Embodiment

A seventeenth embodiment will be described with reference to FIGS. 22Aand 22B. In the seventeenth embodiment, at least a surface of anintermediate structure 510 may be formed of a material to which thetarget material 200 is hard to adhere. FIGS. 22A and 22B are descriptiveviews showing the tip of the target supply unit 120 in enlargement.

The surface of the intermediate structure 510 may be coated with amaterial with a low wettability to the target material 200 (materialwith a large contact angle to the target material). The entireintermediate structure 510 may be formed of a material with a lowwettability to the target material 200. When the target material 200 istin, the material with a low wettability to the target material 200 mayinclude, for example, molybdenum, tantalum, alumina ceramics, and soforth. Alternatively, the intermediate structure 510 may be configuredof ceramics containing, as a main component, silicon carbide, siliconnitride, aluminum oxide, zirconium oxide, diamond, silicon oxide,molybdenum oxide, tantalum oxide, tungsten oxide, and so forth.

As shown in FIG. 22A, the intermediate structure 510 may be formed in adownwardly converging frustoconical shape. There may be a case where theentirety or part of the droplet 201 discharged through the nozzle 122Bmay adhere to an upper surface of the intermediate structure 510 andbecome the foreign matter 210. The foreign matter 210 may slide on thesurface of the intermediate structure 510, and drop through the opening501.

As shown in FIG. 22B, an intermediate structure 511 may be formed in anupwardly converging frustoconical shape. In this case, the foreignmatter 210 adhering to the surface of the intermediate structure 511 mayslide toward an outer edge of the intermediate structure 511, and dropfrom the outer edge of the intermediate structure 511. The foreignmatter 210 adhering to an area near the opening 501 may drop through theopening 501.

The seventeenth embodiment thus configured may be combined with otherembodiments of this disclosure, with which the maintenance on the targetsupply unit 120 can be performed automatically, and the usability of thedevice may be increased.

Eighteenth Embodiment

An eighteenth embodiment will be described with reference to FIGS. 23Athrough 23C. In the eighteenth embodiment, the foreign matter 210 in thenozzle unit 122 may be discharged outside in the recovery mode.

FIGS. 23A through 23C are descriptive views showing a method for pushingout the foreign matter 210 through the nozzle unit 122. As shown in FIG.23A, There may be a case where the foreign matter 210 is suspendedaround the nozzle unit 122. Thus, as shown in FIG. 23B, the pressure inthe nozzle unit 122 may temporarily be increased. With this, as shown inFIG. 23C, the foreign matter 210 suspended in the nozzle unit 122 may bepushed out.

Several methods are conceivable as a method for discharging the foreignmatter in the nozzle unit 122 to the outside. A first method is a methodin which gas pressure applied into the storage 121B is increased,whereby the pressure inside the nozzle unit 122 is increased and theforeign matter 210 is discharged. A second method is a method in which amember constituting a channel for the target material, including thenozzle unit 122, is deformed within a range of elastic deformation andthe volume inside the channel for the target material is decreased,whereby the pressure inside the nozzle unit 122 is increased and theforeign matter 210 is discharged. A third method is a method in which anelectrode such as the electrode unit 123 is provided and the foreignmatter 210 is discharged with electrostatic attractive force. Theabove-described methods may be combined.

With the eighteenth embodiment thus configured as well, the maintenanceon the target supply unit 120 can be performed automatically, and theusability of the device may be increased.

Nineteenth Embodiment

A nineteenth embodiment will be described with reference to FIGS. 24through 25B. In the nineteenth embodiment, a trap unit 600 for trappingthe foreign matter 210 removed from the target supply unit 120 may beprovided. FIG. 24 is a descriptive view schematically showing therelationship among the target supply unit 120, the trap unit 600, andthe collector mirror 130. FIGS. 25A and 25B are descriptive viewsshowing the configuration for switching the positions of the trap unit600. It is to be noted that a collection unit 170 shown in FIG. 24 maybe a device for collecting a droplet 201 that is not irradiated with alaser beam, from among droplets 201 outputted from the target supplyunit 120 in the normal mode.

As shown in FIG. 24, the trap unit 600 may be provided between thetarget supply unit 120 and the collector mirror 130. The trap unit 600may receive the foreign matter 210 removed and dropped from the targetsupply unit 120, and prevent the foreign matter 210 from adhering to thecollector mirror 130.

The trap unit 600 may, for example, include a shutter 601 and a motor602 for rotating the shutter 601. The shutter 601 may be formed in aflat plate shape, or in a dish-like shape with the center thereof beingrecessed. When the shutter 601 is formed in the dish-like shape, theforeign matter 210 collected on the shutter 601 can be furthereffectively prevented from being scattered around by centrifugal forcegenerated when the shutter 601 is rotated.

FIG. 25A shows the position of the shutter 601 in the recovery mode.This position is referred to as a first position or a trap position.When the shutter 601 is at the first position, the foreign matter 210removed from the target supply unit 120 may be trapped on the shutter601. With this, the foreign matter 210 can be prevented from adhering tothe collector mirror 130.

FIG. 25B shows the position of the shutter 601 in the normal mode. Thisposition is referred to as a second position or a normal position. Whenthe shutter 601 is at the second position, the droplet 201 outputtedfrom the target supply unit 120 can move toward the plasma generationregion 202. Accordingly, when the shutter 601 is at the second position,the path of the droplet 201 outputted from the target supply unit 120may not be blocked, and the EUV light may be generated in the plasmageneration region 202.

With the nineteenth embodiment thus configured, the foreign matter 210removed from the target supply unit 120 can be prevented from adheringto the collector mirror 130. Accordingly, by desirably combining thisembodiment with any of the above-described embodiments for removing theforeign matter 210, the efficiency of the maintenance work can beincreased, and the usability of the device may be increased.

Twentieth Embodiment

A twentieth embodiment will be described with reference to FIG. 26. Inthe twentieth embodiment, a mirror protection unit 610 for protecting asurface of the collector mirror 130 may be provided. FIG. 26 is adescriptive view schematically showing the relationship among the targetsupply unit 120, the mirror protection unit 610, and the collectormirror 130.

The mirror protection unit 610 may include a dome-like shutter 611 and amotor 612 for rotating the shutter 611. In the normal mode, the shutter611 may stand by at a position at which the shutter 611 does not blockthe optical path of the EUV light. The shutter 611 may preferably standby at a position at which the shutter 611 does not adversely affect thegeneration of plasma, the emission of the EUV light, and the collectionof the EUV light.

In the recovery mode, the motor 612 may move the shutter 611 to aposition at which the shutter 611 covers a reflection surface of thecollector mirror 130. With this, the shutter 611 may shield between thecollector mirror 130 and the target supply unit 120, and protect thecollector mirror 130 from the foreign matter 210 removed from the targetsupply unit 120. The twentieth embodiment thus configured may yield anadvantage similar to that of the nineteenth embodiment.

Twenty-First Embodiment

A twenty-first embodiment will be described with reference to theflowchart shown in FIG. 27. Embodiments described below including thetwenty-first embodiment are specific examples of the recovery flagsetting processing described with reference to FIG. 3.

If the target supply unit 120 is activated (S100: YES), the recoverycontrol unit 301 may increment the value of a counter NS that integratesthe number of activation times by one (NS=NS+1, S101). Then, therecovery control unit 301 may determine whether or not the number ofactivation times NS has reached a predetermined threshold NSt (NS≧NSt,S102).

If the number of activation times NS has reached the threshold NSt(S102: YES), the recovery control unit 301 may set the recovery flag(S103), and reset the number of activation times NS(S104).

In this way, the recovery flag may be set when the target supply unit120 is activated by the predetermined number, and thus the maintenanceon the target supply unit 120 can be performed automatically.

Twenty-Second Embodiment

A twenty-second embodiment will be described with reference to theflowchart shown in FIG. 28. The recovery control unit 301 may include atimer, and may time an elapsed time Tr since the execution of thepreceding recovery operation (or the execution of the maintenance work)(S110). The recovery control unit 301 may determine whether or not theelapsed time Tr has reached a predetermined elapsed time Trt (Tr≧Trt,S111).

If the elapsed time Tr since the execution of the preceding recoveryoperation has reached the predetermined elapsed time Trt (S111: YES),the recovery control unit 301 may set the recovery flag (S112), andreset the elapsed time Tr (S113).

In this way, the recovery flag may be set when the elapsed time Tr sincethe execution of the preceding recovery operation has reached thepredetermined elapsed time Trt, and thus the maintenance on the targetsupply unit 120 can be performed automatically.

Twenty-Third Embodiment

A twenty-third embodiment will be described with reference to theflowchart shown in FIG. 29. The recovery control unit 301 may monitorthe output of the droplet 201 from the target supply unit 120 (S120). Ifthe droplet 201 is outputted from the target supply unit 120 (S120:YES), the recovery control unit 301 may increment the value of a counterDPN that integrates the number of output times by one (DPN=DPN+1, S121).

The recovery control unit 301 may determine whether or not the number ofdroplet output times DPN has reached a predetermined number of outputtimes DPNt (DPN≧DPNt, S122). The number of droplet output times may becalculated as the number of times an output pulse of the pulse controlunit 320 shown in FIG. 1 and a detection signal of the positiondetection sensor 340 are both detected. If the number of droplet outputtimes DPN has reached the predetermined number of output times DPNt(S122: YES), the recovery control unit 301 may set the recovery flag(S123), and reset the number of droplet output times DPN(S124).

In this way, when the number of output times DPN of the droplets 201from the target supply unit 120 has reached the predetermined numberDPNt, the maintenance on the target supply unit 120 can be performedautomatically.

Twenty-Fourth Embodiment

A twenty-fourth embodiment will be described with reference to theflowchart shown in FIG. 30. The recovery control unit 301 may measurethe position of the droplet 201 via the position measuring unit 302(S130). The recovery control unit 301 may determine whether or not thepositional accuracy of the droplet 201 is within a predetermined range(S131). Further, whether or not the droplet 201 has been outputted withan output instruction from the droplet controller 310 may be determined.

If the positional accuracy of the droplet 201 is not within thepredetermined range (S131: NO), the recovery control unit 301 may setthe recovery flag (S132). A condition under which it is determined as NOin S131 may be a case in which the droplet 201 is not detected althoughthe output instruction is given by the droplet controller 310. In thisway, when the position of the droplet 201 outputted from the targetsupply unit 120 becomes unstable or when the droplet is not outputted,the maintenance on the target supply unit 120 can be performedautomatically.

This disclosure is not limited to the above-described embodiments. Thoseskilled in the art can make various additions, modifications, and soforth within the scope of this disclosure. For example, theabove-described embodiments may appropriately be combined.

For example, an embodiment in which a foreign matter is heated (secondembodiment, third embodiment, fourth embodiment, fifth embodiment, sixthembodiment) may appropriately be combined with an embodiment in whichinert gas is blown against a foreign matter (seventh embodiment, eighthembodiment, ninth embodiment, tenth embodiment, eleventh embodiment,twelfth embodiment). This is because the foreign matter can be easilyremoved if the inert gas is blown while flowability is increased byheating the foreign matter.

Further, in the thirteenth embodiment in which the inert gas is flowedin from the outside of the nozzle, or in the fourteenth embodiment inwhich the foreign matter in the nozzle is sucked, the configuration forheating the foreign matter may additionally be provided.

Furthermore, by combining the first through sixteenth embodiments withthe seventeenth embodiment in which the material with the lowwettability to the target material is used for the intermediatestructure, the foreign matter adhering thereonto can be more effectivelyremoved.

Further, by combining the first through eighteenth embodiments with thenineteenth embodiment in which the foreign matter trap unit is provided,or with the twentieth embodiment in which the mirror protection unit isprovided, the foreign matter removed from the target supply unit can beprevented from adhering to the collector mirror.

The above description is non-limiting and is illustrative. Accordingly,it may be apparent to those skilled in the art that variousmodifications can be added to the embodiments of this disclosure withoutdeparting from the scope of this disclosure. The terms used herein andthe appended claims should be interpreted as “non-limiting.” Forexample, the terms “include” or “included” should be interpreted as “notlimited to the elements described as being included.” The term “have”should be interpreted as “not limited to the elements described as beinghad.” Further, the modifier used herein and the appended claims “a/one”should be interpreted as “at least one” or “one or more.”

1-30. (canceled)
 31. A chamber apparatus used with a laser apparatus,comprising: a chamber provided with at least one inlet for introducingthereinto a laser beam outputted from the laser apparatus; a targetsupply unit provided to the chamber for supplying a target material to apredetermined region in the chamber; and a position measuring unit formeasuring a position of the target material supplied from the targetsupply unit into the chamber, wherein the target supply unit includes anozzle, and a remover which is configured to remove a foreign matteradhering to the nozzle or an intermediate structure provided to face thenozzle.
 32. The chamber apparatus according to claim 31, furthercomprising a recovery control unit for instructing the target supplyunit to execute recovery operation if a predetermined condition is met;and a recovery unit for executing the recovery operation in response tothe instruction from the recovery control unit, wherein a measurementresult by the position measuring unit is inputted to the recoverycontrol unit, and the predetermined condition is that a position of thetarget material supplied into the chamber is in a predetermined positionrange.
 33. The chamber apparatus according to claim 31, furthercomprising a recovery control unit for instructing the target supplyunit to execute recovery operation if a predetermined condition is met;and a recovery unit for executing the recovery operation in response tothe instruction from the recovery control unit, wherein the recoverycontrol unit determines whether or not it is timing at which therecovery operation is executed if the predetermined condition is met,and instructs the recovery unit to execute the recovery operation if itis determined that it is the timing at which the recovery operation isexecuted.
 34. The chamber apparatus according to claim 31, furthercomprising: a recovery control unit for instructing the target supplyunit to execute recovery operation if a predetermined condition is met;and a recovery unit for executing the recovery operation in response tothe instruction from the recovery control unit, wherein the recoveryunit includes a vibrator provided at the nozzle, and a power supplyconnected to the vibrator.
 35. The chamber apparatus according to claim31, further comprising: a recovery control unit for instructing thetarget supply unit to execute recovery operation if a predeterminedcondition is met; and a recovery unit for executing the recoveryoperation in response to the instruction from the recovery control unit,wherein the recovery unit includes a heater provided at the nozzle, anda power supply connected to the heater.
 36. The chamber apparatusaccording to claim 31, further comprising: a recovery control unit forinstructing the target supply unit to execute recovery operation if apredetermined condition is met; and a recovery unit for executing therecovery operation in response to the instruction from the recoverycontrol unit, wherein the intermediate structure is provided at thetarget supply unit, the intermediate structure being arranged so as tobe located between the target supply unit and the predetermined regionin the chamber, and the recovery unit includes a heater provided at theintermediate structure, and a power supply connected to the heater. 37.The chamber apparatus according to claim 31, further comprising: arecovery control unit for instructing the target supply unit to executerecovery operation if a predetermined condition is met; and a recoveryunit for executing the recovery operation in response to the instructionfrom the recovery control unit, wherein a heater and the intermediatestructure are provided at the target supply unit, the intermediatestructure being arranged so as to be located between the target supplyunit and the predetermined region in the chamber, and the recovery unitincludes a heating pipe provided at the intermediate structure, and achannel for providing communication between the heating pipe and theinterior of the target supply unit.
 38. The chamber apparatus accordingto claim 31, further comprising: a recovery control unit for instructingthe target supply unit to execute recovery operation if a predeterminedcondition is met; and a recovery unit for executing the recoveryoperation in response to the instruction from the recovery control unit,wherein the intermediate structure is provided at the target supplyunit, the intermediate structure being arranged so as to be locatedbetween the target supply unit and the predetermined region in thechamber, and the recovery unit includes an electromagnetic wave sourcefor outputting an electromagnetic wave toward the intermediatestructure.
 39. The chamber apparatus according to claim 31, furthercomprising: a recovery control unit for instructing the target supplyunit to execute recovery operation if a predetermined condition is met;and a recovery unit for executing the recovery operation in response tothe instruction from the recovery control unit, wherein the intermediatestructure is provided at the target supply unit, the intermediatestructure being arranged so as to be located between the target supplyunit and the predetermined region in the chamber, and the recovery unitincludes at least one gas pipe provided at the intermediate structure,and a gas source connected to the at least one gas pipe.
 40. The chamberapparatus according to claim 31, further comprising: a recovery controlunit for instructing the target supply unit to execute recoveryoperation if a predetermined condition is met; and a recovery unit forexecuting the recovery operation in response to the instruction from therecovery control unit, wherein the intermediate structure is provided atthe target supply unit, the intermediate structure being arranged so asto be located between the target supply unit and the predeterminedregion in the chamber, and the recovery unit includes at least one gaspipe arranged between the intermediate structure and an end of thetarget supply unit, and a gas source connected to the at least one gaspipe.
 41. The chamber apparatus according to claim 31, furthercomprising: a recovery control unit for instructing the target supplyunit to execute recovery operation if a predetermined condition is met;and a recovery unit for executing the recovery operation in response tothe instruction from the recovery control unit, wherein the recoveryunit includes a cover unit for airtightly defining a predetermined spacearound the nozzle, a gas supply unit for supplying inert gas into thepredetermined space, and an open/close mechanism for opening and closingthe cover unit.
 42. The chamber apparatus according to claim 41, whereinthe gas supply unit supplies the gas into the predetermined space suchthat pressure in the predetermined space becomes higher than pressure inthe target supply unit.
 43. The chamber apparatus according to claim 41,wherein a trap for trapping the foreign matter is provided in the targetsupply unit.
 44. The chamber apparatus according to claim 31, furthercomprising: a recovery control unit for instructing the target supplyunit to execute recovery operation if a predetermined condition is met;and a recovery unit for executing the recovery operation in response tothe instruction from the recovery control unit, wherein the recoveryunit includes a suction tube provided so as to penetrate through a wallportion of the target supply unit and having one end extending to anarea near the nozzle, and a suction pump provided at the other end ofthe suction tube.
 45. The chamber apparatus according to claim 44,wherein the recovery unit further includes a collection tank provided atthe other end.
 46. The chamber apparatus according to claim 31, whereinthe target supply unit includes a pressure control unit for controllingpressure in the target supply unit, and a gas supply unit for supplyinggas into the target supply unit.
 47. The chamber apparatus according toclaim 31, wherein the intermediate structure is provided at the targetsupply unit, the intermediate structure being arranged so as to belocated between the target supply unit and the predetermined region inthe chamber, and at least a surface of the intermediate structure isconfigured of a material with low wettability to the intermediatestructure.
 48. The chamber apparatus according to claim 47, wherein theintermediate structure is provided such that the surface thereof isinclined with respect to the gravity direction.
 49. The chamberapparatus according to claim 47, wherein the material is a materialcontaining at least any of molybdenum (Mo), tungsten (W), tantalum (Ta),titanium (Ti), stainless steel, diamond, silicon carbide, siliconnitride, aluminum oxide, zirconium oxide, diamond, silicon oxide,molybdenum oxide, tantalum oxide, and tungsten oxide.
 50. The chamberapparatus according to claim 31, wherein the chamber includes a trapunit movably arranged between the target supply unit and thepredetermined region in the chamber, and a motor connected to the trapunit.
 51. The chamber apparatus according to claim 50, wherein the motormoves the trap unit to a first position when the recovery operation isexecuted, and moves the trap unit to a second position when the recoveryoperation is not executed.
 52. The chamber apparatus according to claim31, wherein the chamber includes a collector mirror for collectingextreme ultraviolet light emitted when the target material is irradiatedwith the laser beam in the chamber, a mirror protection unit movablydisposed at a reflection surface side of the collector mirror, and amotor connected to the mirror protection unit.
 53. The chamber apparatusaccording to claim 52, wherein the motor moves the mirror protectionunit to a third position when the recovery operation is executed, andmoves the mirror protection unit to a fourth position when the recoveryoperation is not executed.